Tanyaratsrisakul Sasipa, Jirapongsananuruk Orathai, Kulwanich Bhakkawarat, Hales Belinda J, Thomas Wayne R, Piboonpocanun Surapon
Institute of Molecular Biosciences, Mahidol University, Salaya, Nakorn Pathom Thailand, Thailand.
Department of Pediatrics, Faculty of Medicine Siriraj Hospital, Mahidol University, Thailand.
Allergy Asthma Immunol Res. 2016 Jan;8(1):55-62. doi: 10.4168/aair.2016.8.1.55. Epub 2015 Jul 14.
The sequence variations of the Der p 2 allergen of Dermatophagoides pteronyssinus diverge along 2 pathways with particular amino acid substitutions at positions 40,47,111, and 114. The environmental prevalence and IgE binding to Der p 2 variants differ among regions. To compare IgE binding to Der p 2 variants between sera from Bangkok, Thailand and Perth, Western Australia with different variants and to determine the variant-specificity of antibodies induced by vaccination with recombinant variants.
The structures of recombinant variants produced in yeast were compared by circular dichroism and 1-anilinonaphthalene 8-sulfonic acid staining of their lipid-binding cavity. Sera from subjects in Bangkok and Perth where different variants are found were compared by the affinity (IC₅₀) of IgE cross-reactivity to different variants and by direct IgE binding. Mice were immunized with the variants Der p 2.0101 and Der p 2.0110, and their IgG binding to Der p 2.0103, 2.0104, and 2.0109 was measured.
The secondary structures of the recombinant variants resembled the natural allergen but with differences in ANS binding. The IC₅₀ of Der p 2.0101 required 7-fold higher concentrations to inhibit IgE binding to the high-IgE-binding Der p 2.0104 than for homologous inhibition in sera from Bangkok where it is absent, while in sera from Perth that have both variants the IC₅₀ was the same and low. Reciprocal results were obtained for Der p 2.0110 not found in Perth. Direct binding revealed that Der p 2.0104 was best for detecting IgE in both regions, followed by Der p 2.0101 with binding to other variants showing larger differences. Mouse anti-Der p 2.0101 antibodies had a high affinity of cross-reactivity but bound poorly to other variants.
The affinity of IgE antibody cross-reactivity, the direct IgE binding, and the specificities of antibodies induced by vaccination show that measures of allergic sensitization and therapeutic strategies could be optimized with knowledge of Der p 2 variants.
屋尘螨Der p 2变应原的序列变异沿两条途径发散，在第40、47、111和114位有特定的氨基酸替换。Der p 2变体的环境流行率和IgE结合在不同地区存在差异。比较泰国曼谷和西澳大利亚珀斯血清中IgE与不同Der p 2变体的结合情况，并确定重组变体疫苗诱导抗体的变体特异性。
通过圆二色性和其脂质结合腔的1-苯胺基萘-8-磺酸染色比较酵母中产生的重组变体的结构。通过IgE与不同变体交叉反应的亲和力（IC₅₀）和直接IgE结合，比较曼谷和珀斯发现不同变体的受试者的血清。用Der p 2.0101和Der p 2.0110变体免疫小鼠，并测量其IgG与Der p 2.0103、2.0104和2.0109的结合。
重组变体的二级结构类似于天然变应原，但在ANS结合方面存在差异。Der p 2.0101的IC₅₀抑制IgE与高IgE结合的Der p 2.0104结合所需浓度比在其不存在的曼谷血清中的同源抑制高7倍，而在同时具有这两种变体的珀斯血清中，IC₅₀相同且较低。在珀斯未发现的Der p 2.0110得到了相反的结果。直接结合显示，Der p 2.0104在两个地区检测IgE效果最佳，其次是Der p 2.0101，与其他变体的结合差异较大。小鼠抗Der p 2.0101抗体具有高交叉反应亲和力，但与其他变体结合较差。
IgE抗体交叉反应的亲和力、直接IgE结合以及疫苗诱导抗体的特异性表明，了解Der p 2变体可优化过敏致敏措施和治疗策略。
